1. Field of the Invention
The present invention relates to a projector-type vehicle headlamp.
2. Related Art
A projector-type vehicle headlamp is generally provided with a projection lens disposed on an optical axis extending in a longitudinal direction of a vehicle, and a light source disposed on a rear side of a rear focal point of the projection lens, and light emitted from the light source is reflected by a reflector toward the optical axis.
Disclosed in JP-A-2002-358806 is a projector-type vehicle headlamp provided with an annular additional lens on an outer periphery of the projection lens so that the light emitted from the light source passes through the additional lens travels toward a front side thereof substantially parallel to the optical axis.
In the vehicle headlamp of JP-A-2002-358806, a first additional reflector is provided on a rear side of the projection lens and in a vicinity of an outer peripheral edge of the projection lens, and reflects direct light emitted from the light source toward a rear side thereof in a direction in which the light is apart from the optical axis. Furthermore, a second additional reflector is provided on a rear side of the first additional reflector, and reflects the light reflected on the first additional reflector toward a front side thereof. Accordingly, the light emitted from the light source is sequentially reflected by the first and second additional reflectors in this order, and then travels to the additional lens.
When a headlamp is lighted, a projection lens of a conventional projector-type vehicle headlamp is illuminated and visible. However, if the additional lens is provided on the outer periphery of the projection lens as disclosed in JP-A-2002-358806, it is possible to increase the light-emitting area of an entire headlamp as much as a quantity of the light passing through the additional lens. As a result, it is possible to improve an appearance of the headlamp with respect to a driver of an oncoming vehicle, thereby further improving the safety conditions during the driving of a vehicle.
However, since the additional lens of the vehicle headlamp disclosed in JP-A-2002-358806 is composed of an annular lens that is formed to have a cross-section of a general plano-convex lens, there has been a problem that it is not possible to dispose the additional lens continuously along a surface shape of the projection lens.
In addition, the light passing through the additional lens is not used as light that radiates toward the front side of the headlamp, but is used to improve the appearance of the headlamp with respect to the driver of the oncoming vehicle. From this point of view, the quantity of the light passing through the additional lens may be small. If the light passing through the additional lens is intense, the headlamp causes glare to the driver of the oncoming vehicle. Accordingly, it is important to consider the driver of the oncoming vehicle.